Very simple issue. I have the useless class:
class Useless{ double field; Useless(this.field);
}I then commit the mortal sin and call new Useless(0);In checked mode (which is how I run my tests) that blows up, because 'int' is not a subtype of type 'double'.
Now, it works if I use new Useless(0.0) , but honestly I spend a lot of time correcting my tests putting .0s everywhere and I feel pretty dumb doing that.
As a temporary measure I rewrote the constructor as:
class Useless{ double field; Useless(num input){ field = input.toDouble(); } }But that's ugly and I am afraid slow if called often. Is there a better way to do this?
49 Answers
Simply toDouble()
Example:
int intVar = 5;
double doubleVar = intVar.toDouble();Thanks to @jamesdlin who actually gave this answer in a comment to my previous answer...
0In Dart 2.1, integer literals may be directly used where double is expected. (See )
Note that this is syntactic sugar and applies only to literals. int variables still won't be automatically promoted to double, so code like:
double reciprocal(double d) => 1 / d;
int x = 42;
reciprocal(x);would fail, and you'd need to do:
reciprocal(x.toDouble());You can also use:
int x = 15;
double y = x + .0;use toDouble() method.
For e.g.:
int a = 10
print(a.toDouble)
//or store value in a variable and then use
double convertedValue = a.toDouble()From this attempt:
class Useless{ double field; Useless(num input){ field = input.toDouble(); }
}You can use the parse method of the double class which takes in a string.
class Useless{ double field; Useless(num input){ field = double.parse(input.toString()); //modified line }
}A more compact way of writing the above class using constructor's initialisers is:
class Useless{ double _field; Useless(double field):_field=double.parse(field.toString());
}Since all divisions in flutter result to a double, the easiest thing I did to achieve this was just to divide the integer value with 1:
i.e.int x = 15;double y = x /1;
There's no better way to do this than the options you included :(
I get bitten by this lots too, for some reason I don't get any warnings in the editor and it just fails at runtime; mighty annoying :(
I'm using a combination:
static double checkDouble(dynamic value) { if (value is String) { return double.parse(value); } else if (value is int) { return 0.0 + value; } else { return value; }
}This is how you can cast from int to doubleint a = 2;double b = a*1.0;
